Survivorship and yield of a harvested population of Forsteronia glabrescens

The exploitation of non-timber forest products may be an opportunity to reconcile the utilization of biological resources with biodiversity conservation. In Southern Brazil, the exploitation of liana stems for handicraft makes up an important part of the income of indigenous Kaingang people. In this study we evaluated the effects of stem harvesting on the survivorship of Forsteronia glabrescens Müll.Arg, the most exploited liana species in the region. We marked and monitored the survivorship, sprouting, changes in stem diameter and resource yield in control and harvested plots with two different resting times–six and twelve months. We associated variables of interest with individual attributes, harvesting regime and vegetation descriptors through linear mixed modelling. Survivorship and resource yield were lower in the harvested groups than in the control group, although the mean stem diameter was higher. Plants with larger stem diameter presented higher survival odds. Either six or twelve months of resting between harvests were not sufficient to recompose the yield and compensate mortality. Harvesting twice a year increases yield but reduces survivorship. Our results point that the sustainable exploitation of F. glabrescens require either large areas, low pressure or resting periods longer than the ones we tested.

→ Thank you for the recognition of our effort and outcome. Figures 2 and 3, the unit of y-axis is incomplete. Is this annual survival and growth? half year, the numbers do not match, because a 65% survival in the semi-annual treatment in the first period could never lead to an ~80% survival for the full year. So my guess is that survival is annualized, but it's important to be clear about this, also in the text.

#3. Figures. In
→ Thank you very much for finding that error in Fig. 2. We had pulled the wrong numbers when building Fig. 2 and apologize for that. The true figures of survival are 66% in the semi-annual treatment in the first period, 73% the second period, and 53% for the whole year. We replaced Fig.   2 and also corrected the values mentioned in the text. All interpretations remain the same, since they were based on the correct figures.
#5. Negative radial growth. I was surprised to see negative radial growth rates. Are these measurement errors, or are they resulting from the fact that growth rate is based on the average diameter? In the latter case, I suggest to avoid confusion by calling this 'Change in mean stem diameter', instead of radial growth. IN any case, this needs to be better explained in the methods section.
→ Thank you for the suggestion. We accepted it and changed the mentions to radial growth in the table 1 and along the text. We agree it will help to avoid confusion. We also explained in Methods that we calculated and then analyzed mean values. In order to standardize the wording and be more precise, we are using "Change in stem length" as well, instead of "stem growth". See also issue #28.
#7. Line 261-262. Strange formulation; I suggest to change to: "Our results raise concerns about the sustainability of stem harvesting of our study species and we therefore call for continued monitoring of harvested populations from this species."

→ Thank you for the recognition of our effort and outcome.
Minor comments: #16. Ln 51-52, 55-56, 224-225: When you say "compensatory and additive mortality", I guess you mean that the recruitment after exploitation can have a compensatory or additive effect on the population. If so, it is not mortality that is compensatory or additive, but the recruitment as a response to the higher mortality generated by the exploitation.
→ We prefer to keep the vernacular wording of the concept -compensatory and additive mortality -as defined in the mentioned literature. Hoping to clarify the idea, we rephrased the statements in lines 51-52, 55-56 to add the term "recruitment". This term is already used in lines 224-225, so we left them unchanged.
→ We rephrased the statement, focusing on the trade-off between recruitment and reproduction.
#18. Ln 100-102: The different number of replicas by treatments could be a problem. I saw that the first reviewer also pointed to this problem. However, you are right; the statistical methods adopted are robust to overcome this shortcoming. However, it is hard to understand why you did that, so you need to justify this decision in the text. #22. Ln 163-164: These results contradict the graphic in Fig. 2. There, the annual harvest had less than 60% of survivorship. The semi-annual has survivorship higher than 72% after 1 yr. → Corrected. Thank you for highlighting this error. We apologize for that. Actually, the numbers in the text were wrong. The correct values, as shown in Fig. 2 #25. Ln 168: Table 1: This is hard to read. Some numbers seem to be out of place. Fix the table.
#26. Ln 170-171: Fig. 2. You say that the y axis is %, but it is not. You have to multiply the number by 100 to get the %.  #36. Ln 234: The sentence "The density of F. glabrescens is similar to that found in other studies" is lost here.
→ We deleted the statement. It is just a minor comment.
#37. Ln 242-244: Expand this idea. It seems an interesting one. → Expanded. We added a comment about the probable population outcome when the relationship is facultative and services, instead o food, are demanded by the parasite, as the case of lianas and trees.
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